task dioesn't show in folder

I create folders for each of my ongoing projects. I then drag tasks into them. This morning, I created a task because I didn't see it in the folder on the "All Tasks" view, even when I expanded the folder. As soon as I dragged the task into the folder, it showed up there twice! That was because it had already been created. So, I navigated to the folder view and expanded the folder for that prject. No tasks were visible there. I went back to the All Tasks view and none of my folders showed any tasks. Why on earth would this be the case?

I am not sure. Maybe you can clarify something for me. When you say that you are dragging tasks into folders, do you really mean that you are dragging subtasks into tasks?

It could be that your filter settings (like a context filter, perhaps) in the folder view are hiding all the tasks, but when you switch into another view that doesn't have this filter enabled, the tasks are displayed.